1. Field of the Invention
The present invention is related generally to methods and apparatus for measuring and calculating exterior and interior ballistics of a projectile and diagnosing the hit parameters of a launcher, and more particularly to a system and methods for measuring and calculating the velocity of said projectile, the time the projectile reaches the point downrange, the downrange point velocity, the energy imparted to the projectile at its exit from a launcher, pressure in a launcher, and determining the location of hit.
2. Description of the Related Art
The following patents are exemplary of current state-of-the-art active devices and methods for either external (outside the gun barrel) or internal (within the gun barrel) ballistics measurements and are not discussed in detail as their differences from the present invention are obvious from a cursory examination: U.S. Pat. No. 2,691,761 (Smith), U.S. Pat. No. 2,735,981 (Schultz et al.), U.S. Pat. No. 3,918,061 (Elgaard), U.S. Pat. No. 4,283,989 (Toulios et al.), U.S. Pat. No. 4,457,206 (Toulios et al.), U.S. Pat. No. 4,486,710 (Schmidt), and U.S. Pat. No. 5,159,396 (Yuhas).
Also known to the applicant are numerous patents relating to passive devices for measuring the velocity of a projectile as it travels between two points. For example, U.S. Pat. No. 4,770,527 (Park), discusses measurement of the velocity of a projectile as it travels between two points. Park includes an apparatus for determining the velocity of a projectile, and comprises optical means for generating a planar array of light beams. Chronographs of the type under particular consideration herein are based on the well-known relationship that velocity of a projectile is equal to the distance traveled by the projectile divided by the time required to travel that distance. Systems such as those shown in U.S. Pat. Nos. 3,824,463; 4,128,76;1; and 4,239,962, all to the present inventor, illustrate devices for this purpose as they have been used in the past. U.S. Pat. No. 4,845,690 to the present inventor discloses an improved chronograph which is capable of indicating the possibility that an error has occurred while the shot sequence is still in progress, essentially on a "real time" basis, so that erroneous data can be eliminated before statistical analysis is accomplished.
There are several prior art devices for tracking moving targets that use acoustic sensors for sensing the acoustic signal and for determining the location at which a projectile passes through or strikes a predetermined plane and which are known to the applicant, however, none of these adequately meet all of the objectives of the present invention. For example, U.S. Pat. No. 5,067,096. and U.S. Pat. No. 5,095,467 (both issued to David P. Olson), both discuss a passive acoustic target tracking system for determining the bearing to a ground object emitting acoustic energy. The system includes three microphones arrayed at corners of an equilateral triangle for sensing acoustic energy emitted by a target, means for generating analog signals, means for conditioning the analog signals, and means for converting the analog signals to digital signals. The bearing to the target is determined trigonometrically from the time differences at which the acoustic wave appears at the microphones. The microphone array is used only to determine the direction from which a planar wave front arrives at the microphones. U.S. Pat. No. 5,025,424 (Rohrbaugh) discloses automatic shock wave scoring apparatus for scoring the "hit" on a supersonic projectile in a target area where the "hit" is determined from the detection of the acoustic ballistic shock wave. The system is based on a rod sensor configuration of non perpendicular curved rod sensors which define a scoring grid based on the intercept of the radial lines from the center of curvature of each curved rod through the tangent impact point (acoustic score point) on each rod. Sensors at the bottom of the target plane can be readily shielded from bullets. The following patents show the historical development of the prior art of devices for and methods of scoring supersonic projectiles: U.S. Pat. No. 2,916,289 (Zito), U.S. Pat. No. 2,925,582 (Mattel, et al), U.S. Pat. No. 2,934,346 (Mongello), U.S. Pat. No. 2,973,964 (Zito), U.S. Pat. No. 3,022,076 (Zito), U.S. Pat. No. 3,217,290 (Sillman), U.S. Pat. No. 3,392,979 (Wilska), U.S. Pat. No. 3,479,032 (Ohlund, et al), U.S. Pat. No. 3,778,059 (Rohrbaugh), U.S. Pat. No. 4,261,579 (Bowyer), and U.S. Pat. No. 5,025,424 (Rohrbaugh).
Pressure transducers (pressure sensors), inclusive resistive strain transducers, are well known in the prior art and need not be described specifically herein.
All of the prior art patents have numerous problems with accuracy being one of the leading problems. To date, no prior art is known that meets all of the objectives of the present invention, that is, to provide a system and method that would measure and calculate exterior and interior ballistics of a projectile and diagnose the hit parameters of a launcher. Moreover, prior art test systems used in the field often fail to provide adequate data for analysis of test performance due to low signal level and infrequent and unpredictable downrange arrival times. Prior art systems are also too costly to produce and have little flexibility in terms of their capability. There is therefore a need for a device which will measure the external and internal ballistics without the need for laborious hand calculations. There is also a need for a versatile device which will provide the accuracy and reliability of measurements. There is also a need for such a device having considerable flexibility for improvements and modifications and which is inexpensive to manufacture.